The gas turbine is to combust fuel with combustion air compressed by the compressor to generate high-temperature and high-pressure combustion gas which is ejected into the turbine where it is expanded to extract an output power for driving an electric generator, a propeller, a vehicle or a machine. In order to obtain an elevated power from gas turbine engines, the generated combustion gas is transported into the turbine without loss. In fact, however, a part of the high-temperature combustion gas from the combustors can leak radially outwardly through gaps between connecting portions of annular members in the gas turbine engine, such as supporting members of the rotor blades and the stator blades. Of course, the more an amount of leak air increases, the more the performance of the gas turbine engine decreases.
To minimize the leakage, JP 08-277701 (A) discloses a mechanism in which a labyrinth seal member for sealing around the turbine rotor is supported by flexible members to move in radial directions. According to this mechanism, when the turbine rotor expands radially by the centrifugal force and/or heat to displace the sealing portions radially, the labyrinth seal member accommodates the radial movements of the sealing positions to maintain the sealing abilities thereof.
The sealing mechanism needs multi-stage tortuous paths to ensure a reliable seal for the turbine rotor which may significantly affect the performance of the gas turbine engine, which increases a size of the labyrinth seal in a axial direction. This causes the sealing members to deform considerably due to small differences of the heat expansions between sealing members and/or of the centrifugal force applied thereto and, as a result, a repetition of the deformations may damage the sealing members.
Accordingly, the present invention is to overcome those problems and for this purpose to provide a seal mechanism of the gas turbine which is capable of accommodating radial expansions of the turbine rotor without accompanying any increase in size in the axial direction and of sealing the turbine rotor in a reliable manner for a long time.